Server virtualisation is the process of encapsulating one or more complete server operating systems, and their applications, within
a virtualised environment on a host server. These virtual servers are separated from the physical hardware on which they live by a
virtualisation layer (or Hypervisor). As well as protecting the host server from virtual server crashes or malicious applications,
this also allows host servers to schedule and allocate resources (CPU cycles, memory and disk space) between the virtual servers. It
also allows the migration of complete virtual machines (VMs) between physical servers.
“Our primary goal is not supporting technology, it is supporting people. Using technology to make their business lives easier
and more productive.”
(Joseph, IT WLR Senior Technology Consultant)
The principle behind virtualisation is the use of software to create a VM that emulates a physical computer. By utilising multiple
VMs at once, the operation of several operating systems and applications simultaneously on a single physical machine is possible.
Running applications on a shared server like this also offers security benefits, such as data being stored centrally, rather than on
multiple desktop machines. Also, VMs are stored as files, which means the process of restoring a failed system can be as easy as
copying a file onto a new machine. Since VMs can have different hardware configurations from the physical machine on which they’re
running, this approach also allows the restoring a failed system onto any available machine. There is no requirement to use a physically
In addition to using virtualisation for servers, it is also possible to use virtualisation for desktop functionality in one of two ways:
Locally virtualised desktops can operate a separate OS environment on individual desktops so in effect, there are multiple desktops
running on one individual client.
A number of desktops which can be operated centrally from servers for individual users (often referred to as a virtual desktop infrastructure
(VDI). These can be standardised to ease administration as well as reduce costs.
Using a VDI, the cost of managing applications can be significantly reduced. Instead of updating each application on each individual
desktop, for example, only the single shared copy on the server needs to be changed. Using simpler desktop operating system images or
specialised desktop devices (thin clients) can also reduce management costs further. In addition, licensing models become much more cost
effective through the use of concurrent licensing.